1. Field of the Invention
The present invention relates generally to quick-connect tubular couplings used on hose assemblies. In particular, the present invention relates to a quick-connect tubular coupling for direct connection to air-conditioning hoses.
2. Description of the Prior Art
As developments are made in the art of automotive air-conditioning systems, the components that go into the make-up of an air-conditioning system must also develop. A reduction in assembly time, ease of assembly, lower cost, lower weight, and improved durability are all goals that engineers strive to accomplish to reduce the cost and improve the quality of these components.
U.S. Pat. No. 4,055,359 to McWethy discloses a quick-connect fitting that claims to accomplish some of the above mentioned objectives. However, advances made in automotive air-conditioning systems require improvements above and beyond what is detailed in the '359 reference. In particular, size and weight reductions have become even more important as fuel economy and emissions restrictions are strictly regulated. Individual components must meet the strictest of size and weight limitations to reduce the overall vehicle weight, improve gas mileage, and reduce vehicle emissions.
The '359 reference discloses a quick-connect tubular coupling having a pair of tubes. A free end of one tube, or inner tube, is telescopically disposed within an end portion of the other tube, or outer tube. The outer tube has a flared end. An annular cage is mounted externally on the inner tube and is axially spaced from the end that is disposed in the outer tube. The cage has a circular spring disposed therein, that engages the flared end of the outer tube. The spring, the cage and the flared end of the outer tube prevent axial movement of one tube relative to the other. O-rings are compressed between the inner and outer tubes as a seal to prevent leakage.
The cage is retained from axial movement along the inner tube by roll-formed upset beads. The upset beads abut outer and inner surfaces of the cage base portion. What is not shown in the '359 reference, is the hose and the means for attaching the hose to the tubular coupling.
In a method presently known in the art, the inner tube further includes an outer sleeve spaced a distance from the free end of the inner tube. A hose is disposed between the inner tube and the outer sleeve and the outer sleeve is crimped around the hose, retaining the hose on the tubular coupling.
Similar to the retention method for the cage, the outer sleeve is retained from axial movement by roll-formed upset beads. Just as the upset beads abut the outer and inner surfaces of the cage base portion, upset beads abut the outer and inner surfaces of the outer sleeve base portion.
Manufacturing the coupling disclosed in the '359 reference involves multiple costly steps and close control of dimensional tolerances. The upset beads must be formed on either side of both the cage and the outer sleeve, necessitating formation of a total of four upset beads. The distance on the tube between the outer sleeve and the cage creates tolerance stack-ups that make dimensional control very difficult and manufacture very expensive. The time involved in completing the necessary tube forming operations is extensive and, as a result, manufacturing costs are high.
In addition, the cage must be spaced a predetermined distance from the outer sleeve in order to accommodate manufacturing of the upset beads. As a result, the coupling is longer, taking up valuable packaging space and adding unwanted weight. Further, because of the extended length of the coupling, the tolerance stack-ups are difficult to control. Accordingly, while the tubular coupling disclosed in the '359 reference has adequate retention and sealing capabilities, there is room for improvement where size and weight constraints are concerned.
What is needed is a closed coupling quick-connect fitting that is compact and lightweight. The fitting must be easy to manufacture and have good retention and sealing capabilities.